This invention relates generally to the mounting and coupling in circuit of electronic components and is particularly directed to an improved arrangement for mounting, cooling and coupling in circuit axial lead electronic components.
A rectifier circuit is used to convert alternating current such as from a line source to a direct current. Rectifier circuits are generally comprised of a diode bridge which makes use of four diodes coupled in such a manner so as to provide a direct current output. The diodes typically used are semiconductors having a pair of axial leads, with each lead extending from opposite ends thereof. When using axial lead diodes, the limiting operating factor of the diode bridge at high currents is the diode junction temperature. Excessively high junction temperatures tend to cause diode failure and result in a corresponding reduction in diode reliability and operating life.
Prior art attempts to reduce diode junction temperature have generally involved the coupling of a heat sink to one or both of the diode leads. However, in the case of diode bridges wherein the four diodes are encapsulated in a single housing, intimate contact between the diodes and a heat sink is generally not possible. Moreover, encapsulation of the bridge components tends to substantially increase their operating temperatures such that an efficient means for cooling these components is essential in this environment. Many prior art semiconductor encapsulation packages include a thermal transfer plate integrally formed with the plastic encapsulation package. The thermal transfer plate is typically connected to an external heat dissipator, or sink. This arrangement, however, suffers from heat dissipation limitations arising from the coupling between the encapsulated device's thermal transfer plate and the external heat dissipator. This coupling typically takes the form of a threaded coupler such as a screw or a solder junction, with both approaches offering only limited heat transfer between the plate and the heat sink.
The present invention is intended to overcome the aforementioned limitations of the prior art and provides various desired operating, structural, manufacturing and assembly characteristics in a mounting, coupling and heat sink assembly for electronic components which may be used in virtually any circuit employing axial lead components, but is described in detail below in an embodiment particularly adapted for use in a rectifying bridge circuit comprised of four axial lead diodes.